1. Field of the Invention
The present invention relates to a liquid crystal display apparatus, and more particularly to a flat type fluorescent lamp capable of enhancing a brightness uniformity and a liquid crystal display apparatus having the same.
2. Description of Related Art
A display apparatus that is suitable with a new technical trend and is required for processing information has been developed to have a variety of shapes and functions and increased information processing speed. Particularly, a flat panel type display apparatus has been applied to a variety of electronic devices due to its features such as light weight, compact size and low power consumption, etc. An LCD (Liquid Crystal Display) apparatus among the flat panel type display apparatuses provides a full color and a high resolution in comparison with a display device such as a CRT (Cathode Ray Tube). Thus, the LCD apparatus has been widely used as display devices.
However, the LCD apparatus is a light-receiving element that cannot emit a light by itself, so that the LCD apparatus requires a light source and an image quality thereof is greatly affected by the light source. The light source is classified into a reflection type that uses an ambient light and a transmission type that uses a backlight. To display an image with high quality, the backlight method in which the light source is disposed at a rear of the LCD panel is widely used. An EL (Electro Luminescence), an LED (Light Emitting Diode), a CCFL (Cold Cathode Fluorescent Lamp) and a HCFL (Hot Cathode Fluorescent Lamp), etc., are used as the light source in the backlight method. The CCFL is advantageous in its long life expectancy, thin thickness and low power consumption, and the like, thus it is used in a TFT-LCD (Thin Film Transistor Liquid Crystal Display).
The CCFL is disposed either as a directly lighting type in which lamps are disposed under the LCD panel or as an edge lighting type in which lamps are disposed adjacent to side portions of a light guide plate. However, where the CCFL is disposed as the edge lighting type, there is a limitation in increasing brightness of the light and where the CCFL is disposed as the directly lighting type, thickness of the LCD apparatus can be increased, and uniformity of the brightness can be deteriorated.
Thus, a flat type fluorescent lamp is widely used as the light source to increase the brightness of the light and to obtain the uniformity of the brightness. The flat type fluorescent lamp is classified into an opposite electrodes disposing type and a surface discharging type.
FIG. 1 is a cross-sectional view showing a conventional flat type fluorescent lamp for the surface discharging type. FIG. 2 is a plan view showing a structure of the flat type fluorescent lamp shown in FIG. 1. Specifically, FIG. 1 is an enlarged view of A in FIG.2.
Referring to FIGS. 1 and 2, the flat type fluorescent lamp 90 includes a first substrate 10, a second substrate 20 separated from the first substrate 10 in a predetermined distance to provide a discharge space 40 between the first and second substrates 10 and 20, a plurality of spacers 30 disposed between the first and second substrates 10 and 20 for supporting the first substrate 10, and a sealing member (not shown) for sealing a side portion of the first and second substrates 10 and 20 to isolate the discharge space 40 from a peripheral space thereof. The second substrate 20 is positioned parallel to the first substrate 10. Also, the flat type fluorescent lamp 90 includes an insulating layer 22 and an electrode protection layer 24.
The first and second substrates 10 and 20 are made of a glass,. A fluorescent layer 12 is formed on a lower surface of the first substrate 10, and a pair of linear electrodes 26 for applying a high voltage to a discharge gas contained in the discharge space are formed on an upper surface of the second substrate 20. The fluorescent layer 12 is formed using green, blue and red phosphors and an organic resin. The linear electrodes 26 include a cathode 26a and an anode 26b separated from the cathode 26a in a predetermined distance, so that a discharging occurs between the cathode 26a and anode 26b. 
Since a pressure inside the discharge space 40 is lower than an atmospheric pressure, if the size of the flat type fluorescent lamp 90 becomes larger, the first substrate 10 is sagged down or may be broken. The spacers 30 support the first substrate 10, thereby preventing the first substrate 20 from being sagged toward the second substrate 20. When a high voltage is applied to the flat type fluorescent lamp, the discharge gas charged in the discharge space 40 is excited and changed into a plasma. An ultraviolet ray is generated during the phase changing, and reacts with the fluorescent layer 12 to generate a visible ray.
However, there is no region into which an electric charge can be constitutively concentrated between the cathode and anode electrodes 26a and 26b in the flat type fluorescent lamp 90. Thus, a density of the plasma is randomly changed in the discharge space positioned between the cathode and anode electrodes 26a and b, which causes an irregular flow of the plasma. As a result, the ultraviolet ray, and the visible ray are irregularly formed, thus the brightness of the light emitted from the fluorescent lamp is not uniform, so that the display quality of the LCD apparatus adopting the conventional flat type fluorescent lamp is lowered.
The present invention provides a flat type fluorescent lamp capable of uniformly generating a light.
The present invention also provides an LCD apparatus capable of increasing brightness and efficiency of the light.
In one aspect of the invention, there is provided a flat type fluorescent lamp comprising: a first substrate having a first fluorescent layer; a second substrate disposed parallel with the first substrate; a discharge space formed between the first and second substrates and containing a discharge material; an electrode part having first and second electrodes parallel to each other for applying a voltage to the discharge space, the first and second electrodes being disposed on the second substrate; and a plurality of barrier ribs disposed in the discharge space, the plurality of barrier ribs being perpendicular to the first and second electrodes and lower and upper surfaces of the plurality of barrier ribs respectively contacting an upper surface of the second substrate and a lower surface of the first substrate, to divide the discharge space into a plurality of discharge areas.
In another aspect, there is provided an LCD apparatus comprising: a backlight assembly for generating a light; a display unit for receiving the light emitted from the backlight assembly and controlling a liquid crystal to display an image; and a receiving container for sequentially receiving the backlight assembly and display unit, wherein the backlight assembly includes a flat type lamp having a first substrate having a first fluorescent layer; a second substrate disposed parallel with the first substrate; a discharge space formed between the first and second substrates and containing a discharge material; an electrode part having first and second electrodes parallel to each other for applying a voltage to the discharge space, the first and second electrodes being disposed on the second substrate; and a plurality of barrier ribs disposed in the discharge space, the plurality of barrier ribs being perpendicular to the first and second electrodes and lower and upper surfaces of the plurality of barrier ribs respectively contacting an upper surface of the second substrate and a lower surface of the first substrate, to divide the discharge space into a plurality of discharge areas.
According to the present invention, plasma converted from the discharge material contained in the discharge space has a uniform density. Also, the barrier ribs can be integrally formed with the first substrate, thereby maintaining uniformity of brightness of the flat type fluorescent lamp in a desirable level and removing a shadow portion which may be caused by an adhesive to fixing the barrier ribs to the first substrate.